CPLEX（默认）无法提取表达式

Question

我是编程初学者，我的代码显示错误 cplex（默认）无法提取表达式。我的模型应该通过比较不同的运输方式来最小化排放成本（帕累托优化）。当我只用最小成本或最小排放量运行模型时，它工作得很好，但是一旦我分别添加排放量或成本的主观因素，就会发生错误。 我用较小的输入数据测试了模型，效果很好。

错误是：

• Cplex（默认）无法提取表达式：emission_constraint: TotalEmission
• CPLEX(default) 无法提取表达式：forall(a in 1..13462) emits_constraint: TotalEmission
• OPL 无法提取表达式：emissions_constraint: TotalEmission

有人可以帮我找出问题所在吗？谢谢！

以下是我的代码的一部分：

 // Parameters
 int a=...; // Set of arcs available from departure to destination
 int m=...; // Set of transport modes for direct shipment (trucks)
 int n=...; // Set of transport modes for multi-mode shipments (train, vessel, airplane)
 range arc =1..a;
 range transport_dir =1..m;
 range transport_mm=1..n;

// decision variables
 dvar boolean Y[arc]; 
 dvar boolean X_dir[arc][transport_dir]; 
 dvar boolean X_mm[arc][transport_mm];

// expression costs
 dexpr float TotalCost_dir = sum(a in arc, m in transport_dir) cost_dir[a][m]*shipments_dir[a]*X_dir[a][m];
 dexpr float TotalCost_mm = sum(a in arc, n in transport_mm) cost_mm[a][n]*shipments_dir[a]*X_mm[a][n];
 dexpr float TotalCost = TotalCost_dir + TotalCost_mm;
 
 //expression emissions
 dexpr float TotalEmission_dir = sum(a in arc, m in transport_dir) emissions_dir[a][m]*shipments_dir[a]*X_dir[a][m];
 dexpr float TotalEmission_mm = sum(a in arc, n in transport_mm) emissions_mm[a][n]*shipments_dir[a]*X_mm[a][n];
 dexpr float TotalEmission = TotalEmission_dir + TotalEmission_mm; 
 
 // objective 
  //minimize TotalEmission;
  minimize TotalCost;

 subject to {
 
 //General Emission constraint - subject to min. cost 
   forall (a in arc)
     emissions_constraint: 
     TotalEmission <= 976222726;}

Answer 1

// Parameters
 int a=5; // Set of arcs available from departure to destination
 int m=6; // Set of transport modes for direct shipment (trucks)
 int n=7; // Set of transport modes for multi-mode shipments (train, vessel, airplane)
 range arc =1..a;
 range transport_dir =1..m;
 range transport_mm=1..n;
 
 int cost_dir[arc][transport_dir];
 int cost_mm[arc][transport_mm];
 
 int emissions_dir[arc][transport_dir];
 int emissions_mm[arc][transport_mm];
 int shipments_dir[arc];

// decision variables
 dvar boolean Y[arc]; 
 dvar boolean X_dir[arc][transport_dir]; 
 dvar boolean X_mm[arc][transport_mm];

// expression costs
 dexpr float TotalCost_dir = sum(a in arc, m in transport_dir) cost_dir[a][m]*shipments_dir[a]*X_dir[a][m];
 dexpr float TotalCost_mm = sum(a in arc, n in transport_mm) cost_mm[a][n]*shipments_dir[a]*X_mm[a][n];
 dexpr float TotalCost = TotalCost_dir + TotalCost_mm;
 
 //expression emissions
 dexpr float TotalEmission_dir = sum(a in arc, m in transport_dir) emissions_dir[a][m]*shipments_dir[a]*X_dir[a][m];
 dexpr float TotalEmission_mm = sum(a in arc, n in transport_mm) emissions_mm[a][n]*shipments_dir[a]*X_mm[a][n];
 dexpr float TotalEmission = TotalEmission_dir + TotalEmission_mm; 
 
 // objective 
  //minimize TotalEmission;
  minimize TotalCost;

 subject to {
 
 //General Emission constraint - subject to min. cost 
   forall (a in arc)
     emissions_constraint: 
     TotalEmission <= 976222726;}

工作正常